It's debatable who has the better physique per se. If your idea of superman is the broad chested 6'3"+ tall figure than you'd go with Reeve.

Cavil has more of that modern gym defined look but he's about 3 inches shorter than reeves.

Cavil obviously has the advantage in the suit department with the modern textures and padding but i don't think he'd look as impressive as reeve did in the old school suit, while i think reeve would arguably look great in the new suit.